| // -*- C++ -*- |
| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___ITERATOR_PROJECTED_H |
| #define _LIBCPP___ITERATOR_PROJECTED_H |
| |
| #include <__config> |
| #include <__iterator/concepts.h> |
| #include <__iterator/incrementable_traits.h> // iter_difference_t |
| #include <__type_traits/remove_cvref.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| #if _LIBCPP_STD_VER >= 20 |
| |
| template <class _It, class _Proj> |
| struct __projected_impl { |
| struct __type { |
| using value_type = remove_cvref_t<indirect_result_t<_Proj&, _It>>; |
| indirect_result_t<_Proj&, _It> operator*() const; // not defined |
| }; |
| }; |
| |
| template <weakly_incrementable _It, class _Proj> |
| struct __projected_impl<_It, _Proj> { |
| struct __type { |
| using value_type = remove_cvref_t<indirect_result_t<_Proj&, _It>>; |
| using difference_type = iter_difference_t<_It>; |
| indirect_result_t<_Proj&, _It> operator*() const; // not defined |
| }; |
| }; |
| |
| // Note that we implement std::projected in a way that satisfies P2538R1 even in standard |
| // modes before C++26 to avoid breaking the ABI between standard modes (even though ABI |
| // breaks with std::projected are expected to have essentially no impact). |
| template <indirectly_readable _It, indirectly_regular_unary_invocable<_It> _Proj> |
| using projected = typename __projected_impl<_It, _Proj>::__type; |
| |
| #endif // _LIBCPP_STD_VER >= 20 |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___ITERATOR_PROJECTED_H |